Elevator systems typically include a machine that moves the elevator car to provide requested elevator service. In traction-based elevator systems, the machine includes a motor and a brake. The motor causes a traction sheave to rotate to move the elevator car. The brake prevents the traction sheave from rotating when the elevator car should remain parked at a landing. There are known techniques to control the motor and brake operation to achieve desired elevator system operation.
The elevator machine had for many years been situated in a machine room above the hoistway. A modern trend in elevator system design is to eliminate the machine room and support the machine in the hoistway. Various approaches have been developed to accomplish that.
One advantage of a machine roomless elevator system is that it requires less building space. One disadvantage is that the machine is now in the hoistway so that any noise associated with machine operation is more likely to be noticeable to passengers in the elevator car. Quiet and smooth operation is desired to provide a desired ride quality. There are challenges associated with maintaining sufficiently low noise levels in machine roomless elevator systems.
The way in which an elevator machine is supported in the hoistway can be a contributor to the noise introduced into the hoistway. The way in which a machine is supported can effectively increase the noise by radiating sound and producing tonal noise that is noticeable to passengers. Some machine frames, which are designed with sufficient structural integrity to support the loads associated with the machine, tend to increase audible noise as the supporting structures radiate sound associated with machine operation.
Example machine frames are shown in the United States Patent Application Publication No. 2006/051251 and the published European Patent Application No. EP 1698581. Those skilled in the art are always striving to make improvements in elevator systems including providing quieter system operation.